In the case of a known apparatus of this type, the sack is passed through a door and put onto a supporting table, and, after closing the door, the sack is cut in two parts by means of a circular knife having a comparatively large diameter. The supporting table consists of two swivel plates defining a flat surface of said supporting table in their starting position. Below said swivel plates, swivelling frames are arranged, which are provided with pricks passing through holes in the swivel plates before said plates are swivelled upwards, said pricks penetrating into the sack in such a way that the two separate sack portions are firmly held during the upward motion of the swivel plates. The two sack portions are emptied due to the force of gravity and, if necessary, also by means of a shaking movement of the swivel plates. When the sack has been emptied, the swivel plates return to their starting positions, and this has also the effect that the pricks are removed from the swivel plates in a downward movement. The empty sack is then transported to an empty sack compacting means by means of a change-over flap, said empty sack compacting means consisting of a worm conveyor which is arranged in a casing.
In the case of this apparatus, there is the risk that parts of the paper sack are torn off and drop into the bulk material so that the further processing of the bulk material is endangered. Moreover, the raised sack portions hang freely on the associated swivel plates so that it can happen that the sack portions are not emptied completely.